Sealed electrical contacts form an important class of electrical contacts extensively used in electronic devices, electrical networks and the like. Since sealed electrical contacts are not exposed to the outside atmosphere, failures due to corrosive atmosphere or oxidation are greatly reduced. However, it is desirable to increase reliability and lifetime at higher switching currents and reduce failures due to organic or carbonaceous contaminants. Also of importance is the increased life of sealed contacts exposed to erosion due to cable discharges. In addition, it is desirable to simplify manufacture and reduce costs of materials without sacrificing operational characteristics and reliability.
An important class of sealed contacts is the reed contact. These types of contacts are often referred to as reed switches and reed relays. They are made of thin metal strips or reeds located in a (generally) inert atmosphere of a sealed envelope. The envelope is generally made of glass. Typically, the reeds enter into the envelope from opposite ends. The reeds are long enough to partially overlap one another and form electrical contacting surfaces. A means is provided for opening and closing the reed contacts. Most often, the reed is made of some resilient magnetic material and a magnetic field is used to move the reeds so that contact is made.
It is advantageous to have electrical contacts in these reed switches that are reliable and will continue to work reliably over long periods of time. In addition, reliable operation is desirable even where high currents and low voltages are used. Electrical contacts are also exposed to erosion from cabled discharges as well as failures from contact sticking. Reduction of the frequency of these failure modes and reduction in the cost of these devices are highly desirable. Typical reed switches are described by S. S. Coffin et al, U.S. Pat. No. 3,495,061 issued Feb. 10, 1970. The use of sputtered ruthenium as a contact material is described by J. A. Augis and L. L. Hines in I. E. E. E. Transactions Vol. CHMT-1 No. 1, March 1978, pages 46-53.